New triterpenoid from Panax ginseng exhibits cytotoxicity through p53 and the caspase signaling pathway in the HepG2 cell line

A new triterpenoid, 20(R),22(),24(S)-dammar-25(26)-ene-3 beta,6 alpha,12 beta,20,22,24-hexanol (1), and three known triterpenoids, beta-D-glucopyranoside,(3 beta,12 beta)-12,20-dihydroxydammar-24-en3-yl,6-acetate (2), 20(R)-ginsenoside Rg(3)(3), and 20(R)-ginsenoside Rh-2(4), were isolated from the leaves of Panax ginseng. Their structures were determined by chemical analysis and spectral methods (IR, 1D and 2D NMR, HR-ESI-MS). Compounds 1-4 were exhibited various degrees of cytotoxicity in the human hepatoma cell line, HepG2. Compound 1 had the highest cytotoxic potency, with an IC50 value of 20.1 mu M, by stimulating p53-mediated cell cycle arrest at the G1 to S phase transition, leading to apoptosis via activation of the caspase signaling pathway.